The half-life of cesium-137 is 30 years. Suppose we have a 150 mg sample. (a) Find the mass (in mg) that remains after t years.

At a particular temperature, the solubility of He in water is 0.080 M when the partial pressure is 1.7 atm. 4.25 atm is the  partial pressure of He would give a solubility of 0.200 M.

Henry's Law is a gas law states that at a constant temperature the amount of gas that dissolved in a liquid is directly proportional to the partial pressure of that gas.

The solubility of gas is directly proportional to partial pressure.

It is expressed as:

[tex]S_{\text{gas}} = K_{H} P_{\text{gas}}[/tex]

where,

[tex]S_{\text{gas}}[/tex] = Solubility of gas

[tex]K_{H}[/tex] = Henry's Law constant

[tex]P_{\text{gas}}[/tex] = Partial pressure of gas

Now put the values in above expression we get

[tex]S_{\text{gas}} = K_{H} P_{\text{gas}}[/tex]

0.080M = [tex]K_{H}[/tex] × 1.7 atm

[tex]K_{H} = \frac{0.080\ M}{1.7\ \text{atm}}[/tex]

      = 0.047 M/atm

Now we have to find the partial pressure of He

[tex]S_{\text{gas}} = K_{H} P_{\text{gas}}[/tex]

0.200 M = 0.047 M/atm × [tex]P_{\text{gas}}[/tex]

[tex]P_{\text{gas}} = \frac{0.200 M}{0.047\ \text{M/atm}}[/tex]

       = 4.25 atm

Thus from the above conclusion we can say that At a particular temperature, the solubility of He in water is 0.080 M when the partial pressure is 1.7 atm. 4.25 atm is the  partial pressure of He would give a solubility of 0.200 M.

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Sodium chloride is white, crystalline solid at room temperature.

It is a compound whose components atoms are sodium and chlorine.

The atoms of the two elements combine chemically through an ionic bond. The sodium donates it valence electron to the chlorine atom.

Thus, sodium chloride is an ionic compound. It has a characteristic white appearance and crystalline structure.

The compound is a solid at room temperature. It has a melting point of 801 °C.

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Blood Alcohol Concentration (BAC) is defined as the ratio of alcohol in the system to Blood in the system.

Blood/Breath Alcohol concentration (BAC) is the quantity of alcohol within the bloodstream or on one's breath. BAC is expressed because of the weight of ethanol, in grams, in 100 milliliters of blood, or 210 liters of breath. BAC can be measured with the aid of breath, blood, or urine exams.

Blood alcohol content material shows the percentage of alcohol that is in a person's bloodstream. BAC is crucial to prosecutors because they accept it as true with it displays how tons an individual is impaired via alcohol.

Human beings making their own alcoholic beverages regularly calculate the percentage of alcohol by way of extent by way of measuring their relative density with a hydrometer or their sugar content material with a refractometer.

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Answer:

write the following as fractions in their simplest form

The final pressure of the nitrogen gas with the increase in volume is 2.91 atm.

Boyle’s law is a gas law that states that the pressure exerted by a gas (of a given mass, kept at a constant temperature) is inversely proportional to the volume occupied by it.

The relation can be given as:

[tex]P_1V_1=P_2V_2[/tex]

The initial pressure of the gas, [tex]P_1[/tex] = 3.72 atm

The initial volume of the gas, [tex]V_1[/tex] = 8.56L

The final volume of the gas, [tex]V_2[/tex] = 10.94 L

Substituting the values, the final pressure [tex]P_2[/tex] is given as:

3.72 × 8.56 = [tex]P_2[/tex] × 10.94

[tex]P_2 =\frac{3.72 * 8.56}{10.94} \\\\P_2 =2.91 atm[/tex]

Therefore, the final pressure of the nitrogen gas with the increase in volume is 2.91 atm.

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The distinguishing characteristics of comets, meteors, and asteroids are its composition.

Asteroids are the fragments of rock that were left over from the creation of the solar system, Meteors are the rocks that enter the atmosphere of the Earth from space while on the other hand, Comets are the remnants of the formation of the solar system that are made of dust, rocks, and ice. All these materials i.e. comets, meteors and asteroids are different from one another due to its structure and chemical composition.

So we can conclude that the distinguishing characteristics of comets, meteors, and asteroids are its composition.

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The attacking reagent which is an electrophile is H+​; option D.

Electrophiles are electron-loving reagents which attack and attach to electron-rich reagents.

Electrophiles usually are positively charged reagents.

Therefore, the attacking reagent which is an electrophile is H+​.

In conclusion, electrophiles are electron-loving reagents.

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A.  This is not a redox reaction. It is an example of combustion.

During the combustion of a hydrocarbon, the hydrocarbon reacts with oxygen to create carbon dioxide, water, and heat.

2C8H18 + 25O2 → 16CO2 + 18H2O

Thus, we can conclude that, this is not a redox reaction. It is an example of combustion.

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Answer:

A: This is not a redox reaction. It is an example of combustion.

Explanation:

The density of the helium gas is 0.487 g/L

Calculation,

According to Ideal gas equation,

PV = nRT             ...(I)

The values of some terms are given as,

P is the pressure = 3 atm

V is the volume = ?

T is the temperature = 27°C = 27°C + 273 = 300 K

R is the universal gas constant = 0.0821 L∙atm∙mol−1∙K−1

n is the number of moles of helium = given mass of helium/molar mass of helium

n is the number of moles of helium = 1 g/ 4 g/mole = 0.25 mole

So, by putting the value of all data given in the equation (i) we get,

3 atm × V = 0.25 mol ×0.0821 L∙atm∙mol−1∙K−1×300 K

V =  0.25 mol ×0.0821 L∙atm∙mol−1∙K−1×300 K/3 atm

V = 2.05 L

The formula of density = given mass /volume = 1g/2.05 L = 0.487 g/L

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Answer:

I dropped a crystal of sodium acetate into the solution it immediately became cloudy again, it became supersaturated.

Explanation:

I used this and scored 100% but if you copy and paste they will flag you for plagiarsm so make sure to rewrite it in your own words.

I dropped a crystal of sodium acetate into the solution it immediately became cloudy again, it became supersaturated.

Chemically known as CH3COONa, sodium acetate is a hygroscopic powder that is very water soluble. The addition of sodium acetate to products like heating pads, food, industries, and concrete is possible.

When administered intravenously, sodium acetate plays a critical role in medicine as an electrolyte replenisher. It is mostly recommended to treat hyponatremic patients' sodium levels. Additionally, it can be used to alkalinize urine and treat metabolic acidosis.

In patients with limited or no oral intake, salt should be added to high volumes of intravenous fluids to prevent or treat hyponatremia. for the patient's needs cannot be addressed by conventional electrolyte or nutrient solutions, it is also helpful as an addition for creating customized intravenous fluid formulas.

Therefore, I dropped a crystal of sodium acetate into the solution it immediately became cloudy again, it became supersaturated.

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The time taken for the reaction to reach equilibrium in this concentration versus time graph is 4.5 seconds and is denoted as option D.

This refers to the duration in which a certain action or activity takes place with its unit being seconds.

From the graph we can deduce that:

This therefore means that the time taken for the reaction to reach equilibrium in this concentration versus time graph is 4.5 seconds.

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Answer: 4.5 is right just took the test.

Explanation:

A chemical reaction occurred because calcium oxide has different properties than calcium and diatomic oxygen. The correct option is A.

A chemical reaction is said to occur when the chemical properties of substances change during the course of the reaction.

From the illustration, the chemical properties of calcium oxide are unique from that of calcium and oxygen. Thus, calcium oxide has become a new substance entirely.

Once a reaction leads to the formation of new substances, such a reaction is a chemical reaction.

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1)The limiting reactant will be aluminum acetate

2) The mass of aluminum hydroxide formed will be 9.75 grams.

The equation of the reaction is as below:

[tex]Al(C_2H_3O_2)_3 + 3NaOH --- > 3C_2H_3NaO_2 + Al(OH)_3[/tex]

The mole ratio of the 2 reactants is 1:3.

Mole of 100 mL. 1.25 mol/L [tex]Al(C_2H_3O_2)_3[/tex] = 0.1 x 1.25 = 0.125 mol

Mole of 300 mL, 2.30 mol/L NaOH = 0.3 x 2.3 = 0.69 mol

Thus, aluminum acetate is limited.

Mole ratio of  [tex]Al(C_2H_3O_2)_3[/tex] and [tex]Al(OH)_3[/tex] = 1:1

Equivalent mole of [tex]Al(OH)_3[/tex] = 0.125 mol

Mass of 0.125 mole [tex]Al(OH)_3[/tex] = 0.125 x 78 = 9.75 grams.

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In the endpoint when the indicator changes color it gives the information that the acid is neutralized by the base.

Titration is also known as titrimetry is a technique where a solution of known concentration is used to calculate the concentration of the unknown solution. Titration is a laboratory technique.

The point at which the indicator changes the color is known as Endpoint.

Thus from the above conclusion we can say that In the endpoint when the indicator changes color it gives the information that the acid is neutralized by the base.

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If chemical A has a toxicity level of one and chemical B has a toxicity level of two and the mixture of these two chemicals has a toxicity level of three, it means that the mixture of these two chemicals form a synergistic mixture.  This is condition is known as synergism.

A synergistic effect is exerted when a greater effect is exerted than the added effect of both the chemicals together. This is applicable for toxic chemicals as well as non-toxic chemicals. Synergism can be dangerous in the case of both toxicology or chemicals in general. The greater effect of toxic chemicals can result in a dangerous mixture, which could prove to have fatal effects in many cases.  The opposite of synergistic effect is antagonistic effect. The antagonistic effect is the effect where the overall effect of these two chemicals would be less than the sum of the effects imparted by the individual chemicals.

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ksp = 2S²

= 2 [ 7.9* 10-⁴ moldm-³ ]²

= 124.82 * 10-⁸ mol² dm-⁶

The term Ksp denotes the solubility product. It is generally used to predict the precipitation of reactions. The  Ksp of PbSO₄ is  6.24 × 10⁻⁷.

The solubility product of a sparingly soluble salt is defined as the product of the molar concentrations of its ions in a saturated solution of it at a given temperature. By knowing the solubility product of a substance, it is possible to predict whether a substance precipitate out or not.

In short, the precipitation of an ionic substance from the solution occurs when the ionic product exceeds the value of its solubility product at that temperature.

Here PbSO₄ dissociates as:

PbSO₄ → Pb²⁺ (aq) + SO₄²⁻ (aq)

Ksp = [Pb²⁺] [SO₄²⁻ ]

= [7. 9 × 10⁻⁴] [7. 9 × 10⁻⁴]

= 6.24 × 10⁻⁷

Thus the value of Ksp is  6.24 × 10⁻⁷.

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The percent yield will be 95.75%

Mass of copper = 0.3295 g

Mass of filter paper + copper (II) oxide = 0.5723

Mass of filter paper only = 0.2568

Mass of copper (II) oxide = 0.5723 - 0.2568 = 0.3155

Percent yield = yield/total x 100%

                      = 0.3155/0.3295 x 100% = 95.75%

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Explanation:

Proton is one of the subatomic particles which has a positive charge. The number of protons present will give the atomic number of the chemical element. Every element will have a unique atomic number. Thus, we can say that protons will determine the identity of an element.

Answer:

[tex]\fbox {kinetic motion}[/tex]

Explanation:

As the trains are clearly in motion, we can understand the these trains possess kinetic energy, which is by virtue of a motion of a body.

Answer:

type of energy that two train have are kinetic energy

Answer: concentration

Explanation:

This is a fact.

The mass of oxygen gas is 26.0 g.

Given,

Volume (V) = 25.0 L

665

Pressure (P) = 665 torr =

760 atm = 0.875 atm

Temperature (T) = 55 C = (55+2730) K = 328 K

Now using the Ideal gas law, calculate the mole of oxygen gas (02)

PV = nRT

atm . L

0.875 atm x 25.0 L = n x 0.082-

X 328K

mole . K

n = 0.813 mole

Using the molar mass of Oz = 32.0 g/mole, Calculate the mass of Oz

mass = 0.813 mole x 32.0 mole

mass = 26.016 g

mass = 26.0 g

The answer is 26.0 g.

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Answer:

benzene molecule

Explanation:

The molecules exhibiting delocalization of electrons will have at least two resonance structures. These two resonance structure are having the equal energy.

Resonance is an electronic property of molecules by which, the sigma bond or pi bond moves from one location to other forming different mesomeric structures of the compound.

For example carbon dioxide can have two resonance structures.The lone pair in oxygen delocalize from one oxygen to the other. The double bond with carbon can be of either side of carbon. Thus one negative charge forms for one oxygen. This charge can be on the second hydrogen too.

In this way free electrons can delocalise through the orbitals and this process make the molecule more stable. The resonance structures together form the canonical structure which is the most probable and stable form of the compound.

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1.001

120.0

Significant figures are used in science to determine the precision of a number. Depending on the decimal point, sig figs are counted in different ways.

Decimal Points

When counting sig figs, you always start at the first non-zero number. However, sometimes you start from the left, other times the right.

Remember to start counting at the first non-zero number.

For people in the Americas, there is a trick to remembering this.

This works because the Pacific ocean is to the left of the Americas, and the Atlantic is to the right.

4 Significant Figures

The number 1.001, has 4 significant figures. Since there is a decimal point, we start counting from the left. The first digit is not zero, so we count all four places as significant.

The number 120.0 also has 4 sig figs. Like the number above, we start counting from the left because of the decimal. The first digit on the left is not zero, so we once again count all 4 digits as significant.

The amount of ethane decreases

increasing the temperature (adding energy), will drive the reaction to the left

C2H4(g) <--> C2H6(g) + 137 kJ

because this reaction is an exothermic reaction and the heat is a product of this reaction, So when the number of temperature increases

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Reaction at anode

2 Br-​ (aq) -----> Br2 (g) + 2e-

The product formed at the anode is Br2 (g).

In chemistry and production, electrolysis is a technique that makes use of direct electric present-day (DC) to power an otherwise non-spontaneous chemical response.

Electrolysis is commercially crucial as a degree inside the separation of factors from clearly going on sources including ores the usage of an electrolytic cell.

The voltage that is wanted for electrolysis to occur is called the decomposition capacity. The word "lysis" way to split or break, so in phrases, electrolysis would imply "breakdown via power".

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Answer: 60.5%

Explanation:

When 30.0 g of carbon is heated with silicon dioxide, 28.2 g of carbon monoxide is produced.  60.5% is the percent yield of carbon monoxide for this reaction.

The % ratio of the theoretical yield to the actual yield is known as the percent yield. It is calculated as the theoretical yield times by 100% divided by the experimental yield. The percent yield equals 100% if the theoretical and actual yields are equal.

SiO₂(s) + 3C(s)→ SiC(s) + 2CO(g)​

moles of carbon =30.0 / 12=2.5moles

3 moles of carbon give 1 moles of SiC

1 mole of carbon will give 1/3 moles of SiC

2.5 mole of carbon will give (1/3)×2.5 =0.83 moles of SiC

mass of  SiC = 0.83× 40.09=33.27

percent yield = (actual yield/theoretical yield) x 100%

percent yield= (28.2 / 33.27)x 100%

percent yield = 60.5%

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A diprotic acid is titrated with a strong base. The pH at the first half-equivalence point is 3.27. The pH at the second half-equivalence point is 8.53. The value of ka2 is 27.89.

pH is used to measure whether the substance is acidic, basic or neutral and the range is 0-14. If the pH is less than 7 then the solution is acidic in nature. if the pH is more than 7 then the solution is basic in solution. If the pH is equal to 7 then the solution is neutral in nature.

To find the polyprotic value

[tex]K_{a_2}[/tex] = pH of first half equivalence point × pH of second half equivalence point

[tex]K_{a_2}[/tex] = 3.27 × 8.53

      = 27.89

Thus from the above conclusion we can say that A diprotic acid is titrated with a strong base. The pH at the first half-equivalence point is 3.27. The pH at the second half-equivalence point is 8.53. The value of ka2 is 27.89.

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Life alters the atmosphere by producing and removing oxygen, carbon dioxide, and methane.

Burning fossil fuels like coal, and natural gas, including oil, solid waste, trees, and other biological materials release carbon dioxide into the atmosphere, along with some chemical reactions.

It is thought that the first billion years of Earth's history saw a lot of volcanic activity. With little to no oxygen, the early atmosphere was presumably primarily composed of carbon dioxide.

Therefore, life alters the atmosphere by producing and removing oxygen, carbon dioxide, and methane.

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Considering the definition of chemical compounds, a group of atoms of more than one elements forms chemical compounds.

Chemical Compounds are substances that are made up of a minimum of 2 elements that have reacted with each other to give another substance different from the initial elements. Elements are held together by what is known as a chemical bond.

In other words, a chemical compound is any substance formed by the union of two or more types of chemical elements, that is, by atoms of two or more different types of chemical elements, joined together by chemical bonds in certain proportions.

A chemical compound can be separated into its constituent elements by chemical reactions.

In summary, a group of atoms of more than one elements forms chemical compounds.

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The statement that best describes what is happening in the following reaction is this is not a redox reaction, It is an example of combustion (option A).

A combustion reaction is a reaction wherein a substance is combined with oxygen, usually at high temperature, releasing heat.

According to this question, octane undergoes a combustion reaction to produce carbon dioxide and water as follows: 2C8H18 + 25O2 = 16CO2 + 18H2O

Therefore, the statement that best describes what is happening in the following reaction is this is not a redox reaction, It is an example of combustion.

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Answer:

A: This is not a redox reaction. It is an example of combustion.

Explanation: